This invention relates to graphic aids and methods and systems associated therewith. Certain features of the invention make it especially useful in fabricating multiple patterns which are discrete but in registry and in which one pattern represents a portion common with all the rest. Such a system is exemplified by two sided or multilayer circuit boards. For simplicity the remainder of this specification will describe the invention as it is specifically applied to fabricating printed circuit patterns and resist patterns. The reader should be aware that the invention can be applied to other similar products.
Many electronic devices such as printed circuits and the like include one or more conductors which are, for example, printed, plated, etched or formed by a chemical deposition process on a base of insulating material. Many such circuits are two-sided or multilayered. A photographic negative or positive which depicts the circuit pattern for the board, the front and back-side of a two sided board or a plurality of layers of a multilayer board, is often utilized in producing a functional printed circuit board. Once the circuit pattern has been prepared on the base of the board, it is frequently necessary to selectively apply solder to particular portions of the circuit patterns to facilitate the making of permanent connections with the circuit board. These are generally pad areas defined by preferably round marks in the pattern. A protective covering of material, generally called a "solder resist" is frequently applied over the printed circuit patterns to conserve solder by covering all but the marked pad areas where solder joints are to be made. The solder resist also helps avoid shorts in the finished product and thus assures maintenance free operation of the board.
Ordinarily, more than one sheet including drawings or other pictorial representations of the circuit patterns and resist marks in accurate relative registration, must be made. To assure accurate relative positions while at the same time conserving time, labor and materials, it is desirable to produce the necessary pictorial representations (i.e., of circuit patterns and resist mark pattern) from a single layout sheet. While techniques have been known heretofore for making front and back-side circuit patterns from one layout sheet, a separate layout sheet has been necessary to produce a pictorial representation of the resist marks that would generate a photographically distinct image from the circuit patterns.
However, because a separate layout sheet was necessary, additional labor, material and time were required, oftentimes without the appropriate degree of accuracy necessary to assure proper alignment of the resist marks with the circuit patterns.